Does commercial ammo availability drive you caliber choice?

How much does commercial availability of loaded ammo drive your decision to use a caliber? Do you make that choice based on either reloading or not reloading. Or do you make that choice if you happen to lose your ammo on a trip and need to buy or borrow?

Don't reload, so yup. Gotta buy guns that I can get ammo for. I'd like to get into reloading eventually, but there's no public ranges where I live so I don't really get a chance to shoot as much as I'd like to.